I'm 18 years old and really want to be a pro baseball player?

I'll just have to agree with many of the answers published before. You should have started playing like 10 years ago. It takes a lot of practice to become a decent baseball player and make a college team, not to mention going pro. If that's what you want, then go ahead and try it, but i've never heard a case of a kid starting to play at your age and making it. It's not a matter of talent at this point, it's a matter of developing your skills and since you're short, you need all the skills you can get...